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Formation Figure Editor

The figure an array draws through its mxt:particle module is a mxt:formation_shape definition of its own — the module's shape names it and the client lays the dust out from its own copy. Save it as data/<namespace>/mxt/formation_shape/<name>.json.

The editor below draws that definition's strokes; Copy JSON gives you the whole entry, wrapper included. Coordinates are in units of the array's radius, so 1 is exactly the ring the array draws and one figure scales with every array that reads it. The board is the array seen from straight above: +X to the right (east), +Z downwards (south), north up, and each axis end carries its compass letter and the coordinate it sits at (1 on the ring, -1 the same distance the other way).

Open the editor in a new window

How to draw​

  • Polyline: click the vertices, then Enter, a right click or a double click ends the stroke and Esc drops it.
  • Circle: press where the centre goes and drag out the radius. The centre need not sit on the controller — which is a snap target of its own, so putting one there is still one click. Dragging the centre or the start point afterwards moves it, resizes it and turns it.
  • Drag a vertex to move it; ⇄ in the list reverses a stroke (so it grows the other way), ✕ removes one, Ctrl+Z / Ctrl+Y undo and redo.
  • Snapping is the three things that make a regular figure exact instead of nearly right: a 0.05 grid, the ring (r = 1), and the N divisions of the circle — N rays out of the controller, ray 0 due east, one every 360/N degrees. The ring and the divisions beat the grid, so a regular vertex is not rounded twice.
  • Generators: Star N/K writes the {N/K} star the way FormationShape builds it, one closed polyline per cycle of the step — 5/2 is the mod's own mxt:five, 6/2 is mxt:six (two triangles), 8/2 is mxt:eight (two squares), and K = 1 is the plain N-gon. N-gon writes one closed polyline and Rays writes the N rays as N strokes. All three are undoable.
  • Paint is per stroke: one hex colour, or a list of {"at": …, "color": …} stops running along the stroke's own length (ascending at, and the outermost colours are held outside the ends). There is no figure-wide colour to fall back to, so a stroke always carries paint — a fresh one is painted in the new strokes colour. The strip below the toolbar is the selected stroke's ramp: click it to add a stop, drag a marker to move one, and + stop / − stop add and drop stops.
  • start / end are the window of the draw-in the stroke belongs to — the figure's progress is mapped onto it, so start: 0.5 keeps a stroke for the second half and two strokes written one after the other take turns. A window has to open (start below end), so the two inputs move out of each other's way instead of crossing.
  • spacing / size are the stroke's own too: how many blocks apart its dusts sit and how big each one is drawn, 0.33 and 2 unless it says otherwise. A sparse outer ring with a dense inner detail is fine, and both fields stay out of the file while they are the defaults.

What it computes​

  • The point count is the game's own arithmetic: one stroke asks for ceil(its length in blocks / its own spacing) + 1 points at the radius you type, so the readout is what one frame of that array asks the client for. One stroke is capped at 2048 points, after which its far end is dropped — the tool reports that before a pack has to.
  • Growth is the game's rule, not a tool setting: every stroke is cut at its own share of the progress, so strokes with the same window grow together. The slider is that progress and Play runs the draw-in the way the game plays it — duration_ticks ticks at 20 a second, from the first point of the first stroke to the last of the last.
  • speed and loop are preview-only (the default 1× is the game's own pace: a duration_ticks: 24000 draw-in is worth slowing down, a 20-tick one worth speeding up), and the clock beside them reads elapsed / duration_ticks. None of the three reaches the file, and duration_ticks is the module's field rather than the figure's.
  • The lines animate too: lines strokes each stroke from its own start to wherever the walk has reached (a circle sweeps by angle, a polyline walks by arc length). With dust off you are watching the figure being written; what has not been reached stays on as a ghost, which keeps a half-drawn figure editable and stops progress 0 from being a blank board.

What it writes​

{
  "strokes": [
    {"type": "mxt:circle", "radius": 1, "color": [{"at": 0, "color": "#80c0ff"}, {"at": 1, "color": "#ffffff"}]},
    {"type": "mxt:polyline", "points": [[1, 0], [-0.809, 0.588], [0.309, -0.951], [0.309, 0.951], [-0.809, -0.588], [1, 0]], "color": "#ffd76a"}
  ]
}

type is a registry id, so the namespace is required: a bare "circle" is minecraft:circle to the mod and fails the whole definition. The editor still reads a bare one and writes it back as mxt:circle.

Only radius (the array's own) and the preview knobs never reach the file — they are here so the count and the dust size are honest.

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